Unable to block IPv6

Hi all,

Some IPv6 traffic still gets through, while I want to block it. But it looks like I'm unable to blacklist these domains when looking at the 'query log'. The IPv4 get blocked just fine. When looking at the 'settings' tab I see under 'upstream DNS Servers' that IPv4 are blocked, but I am unable to click on the IPv6 option..

How to block IPv6 traffic for these domains where I want it to be blocked?